This invention relates to inflatable sealing and positioning devices used in grouting operations. More specifically, the invention relates to inflatable grouting bags for use in slipliner grouting operations for the repair of sewer and drain pipes.
Many cities and municipal utility districts are having to repair sanitary and storm sewers. A leaking sewer will typically allow sand, clays, silts and other materials to seep into the sewer. The subsequent flow of water through the sewer carries such materials away so that with time voids are created around the exterior of the sewer which are not usually noticed until buildings, roadways or houses are either damaged or in danger of damage due to subsidence.
Alternately, sewer failure may be caused by the chemical attack of the sewer or improper installation of the sewer.
With respect to chemical attack, sanitary sewers and, ocassionally, storm sewers will be subjected to corrosive gases, such as hydrogen sulfide. Typically, concrete sewers are lined with a corrosion proof liner of flexible plastic which, when intact, prevents the corrosion of the sewer. When the corrosion liner fails, it ultimately allows the attack and failure of the sewer with subsequent exchange of fluids and solids between the sewer and surrounding earth.
Regarding improper installation of the sewer, if jointed reinforced concrete sewer pipe is improperly installed, buoyancy and gravity forces on the sewer pipe may cause damage to the sewer pipe, cause sewer pipe movement and may cause sewer pipe joints to open thereby allowing the exchange of fluid and solids with the surrounding earth.
A typical repair procedure for sewers involves the placement of a liner pipe of plastic material, such as fiberglass, smooth wall polyethylene, or composites of polyethylene and polyproplene, inside the existing sewer. After the plastic material pipe has been placed inside the sewer, the annulus between the liner pipe and sewer is filled with a cementitious grout. This procedure of lining the sewer is commonly called slip lining.
As most slip lining operations are carried out with the sewer in service, the slip liner is installed with fluid flowing through the sewer, slip liner and annulus. After the ends of the sewer and slip liner are mechanically sealed, the fluid flow is diverted into the slip liner, and the annular space between the slip liner and sewer, being partially filled with water, can be grouted.
In slip liner grouting operations some problems that exist are grout placement, floation of the slip liner during grouting operations and bulkhead installation and sealing. Regarding grout placement problems, the slip liners are very easily damaged during grouting operations due to the hydrostatic pressure of the grout collapsing the slip liner. Typically, hydrostatic pressure differentials of five (5) to ten (10) pounds per square inch (psi) pressure may cause the slip liner to collapse. With respect to floation of the slip liner during grouting, the buoyancy force on the slip liner may distort the slip liner locally or may cause misalignment of the slip liner within the sewer which may affect the flow characteristics of the slip lined sewer. Finally, bulkhead installation and sealing may be a problem in installing a slip liner in a sewer as low viscosity grouts are difficult to contain in the annulus between the slip liner and sewer at the bulkhead necessary for grouting operations.